PROJECT SUMMARY Although cigarette smoking rates have declined in the US over the past 50 years, there has been an upturn in smoking among military personnel in the last several decades. With over 8 million Veteran enrollees, the Veterans Health Administration serves 75% of low-income and disabled Veterans. Less than 5% of Veterans receiving care through VHA access intensive treatment for smoking cessation, and these services employ a standard approach to cessation counseling that is most relevant for smokers who are ready to quit. To optimize acceptability, reach, and effectiveness, cessation treatments for Veteran smokers should be appropriate for all levels of readiness to quit. A web-based Acceptance and Commitment Therapy program, Flexiquit, has shown great promise in increasing quit rates for smokers in all stages of readiness to quit (52% vs. 14% in a wait-list control group). Web-based delivery makes the program readily scalable to the population level. In this study, we propose development and pilot testing of Vet Flexiquit, an adaptation of Flexiquit for US Veteran cigarette smokers. The study will be conducted in two phases. The first phase will consist of adaptation and iterative usability testing with low-income Veteran smokers (n=20). The second phase will be a pilot feasibility trial (n=50) comparing Vet Flexiquit to the SmokefreeVET web site. The primary goals of the pilot study are to compare Vet Flexiquit to SmokefreeVET on acceptability (i.e., user satisfaction and number of log-ins) and efficacy for impacting theory-based change processes and promoting smoking cessation. This pilot project is significant and innovative in four key respects: (1) it addresses the top cause of cancer and other preventable diseases among socioeconomically disadvantaged US Veterans served by VHA, (2) it applies a novel treatment approach and advances the science of ACT for smoking cessation by testing its effectiveness for smokers at all stages of readiness to quit rather than only among smokers who are ready to quit, (3) web- based delivery has high potential reach, cost-effectiveness, and scalability within VHA, a health care setting where tobacco cessation is under-resourced; and (4) gamification and inclusion of virtual coaches as engagement strategies are substantially different than standard web-based tobacco treatments, including SmokefreeVET. If found to be effective in a larger trial, Vet Flexiquit would be well-positioned for VHA-wide scale-up due to its low maintenance cost and high potential reach, and the core program could be built upon in innovative ways (e.g., capability for virtual coaches to understand and respond to natural language) to further improve engagement and outcomes.